Low Vision Assessment and Rehabilitation

Initial Low Vision Assessment

What is Low Vision?

Low vision, or vision impairment, is a term used to describe varying degrees of
vision loss, up to but not including total blindness, caused by disease, trauma,
or a congenital disorder. Vision loss may be due to:

visual field defects (contraction of the visual
area seen, or defects within the normal span of vision),

decreased contrast sensitivity (reduced ability to discriminate an object
against a similarly-colored background),

loss of color perception,

or commonly two or more of the above.

Many agencies define low vision as either

a visual acuity of 20/70 or worse
in the better eye using a best-corrected spectacle correction, or

visual fields of 20° (twenty degrees) or less.

However, a more functional definition is that low vision comprises
any vision loss that adversely affects the performance of daily activities.

Low vision must not be confused with legal blindness which is defined as:

visual acuity
of 20/200 or worse in the better eye with correction, or

visual fields of 20° or
less in the better eye.

A patient who is legally blind but has some vision would
be considered "Low Vision," but many patients with "Low Vision" are not legally blind.
Legal blindness of 20/200 is certainly not a complete loss of sight, which is
considered as total loss of all vision (no light perception). In fact, if
placed on a continuum between normal vision and no light perception, legal
blindness would be closer to normal sight. Thus a person can be
"legally blind," but still function relatively well visually,
although constrained by the inability to read unless they have low vision rehabilitation, and
by the inability to meet visual requirements for driving.

People with more severe or with total visual loss require
non-visual solutions for their disability. This Low Vision website is
primarily designed to aid individuals with partial sight.